Manufacture of zinc oxid.



J. A. SINGMASTER.

MANUFACTURE OF ZINC OXID. APPLICATION FILED JAN. 9, 1912.

Patented Oct. 6, 1914.

J A. SINGMASTER. MANUFACTURE OF ZINC OXID.

- urmcumn mum JAN. 9. 1912. 1,1 12,853. Patented 00b. 6, 1914.

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J. A. SINGMASTER.

MANUFACTURE or zmc 0x11).

APPLICATION IILED JAR. 9,1912.

1, 1 1 2,853. Patented Oct. 6, 1914.

10 SHEETS-$52121 3.

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J. A. SINGMASTER.

MANUFACTURE OF ZINC OXID.

V APPLIOATION FILED JANA9,1912. 1,112,853.

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10 SHEETS-SHEET 4 5] vwe wlioz J3 f/ngmosfer %13 5/3 tozuurs J. A.SINGMASTER.

MANUFACTURE OF ZINC OXID.

APPLICATION FILED JAN. 9, 1912. 1,1 12,853.

J. A. SINGMASTER.

MANUFACTURE OF ZINC OXID.

AIPLIOATIOI 111.111) $11!. a, 1912.

1,1 12,853. Patented Oct. 6, 1911 V77/ZY/777 awvomioz f \f/bymas/cr J.A. SINGMASTER.

MANUFACTURE OF zmc 0x11).

Patented Oct. 6, 1914,

10 BHEB'I'B8HBET 8.

APPLICATION FILED JAN. 9, 1912.

WNW Leases J. A. SINGMASTER. MANUFACTURE OF ZINC oxm' APPLICATION FILEDJAB. 9, 1912. 1,1 12,853. Patented Oct. 6, 1914.

10 SHEETS-SHEET 8.

10 BHBETSBHEET 10.

Patented Oct. 6, 1914.

J. A. SINGMASTER.

MANUFACTURE OF ZINC OXID- APPLICATION FILED JAN. 9, 1912. 1 1 1 2,853.

ED STATES PATENT OFFICE.

JAMES ARTHUR SINGMASTER, OE PALMERTON, PENNSYLVANIA, ASSIGNOR TO NEWJERSEY ZINC COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

MANTJ'IIF'AC'I'UIEtE OF ZINC OXID.

Specification of Letters Patent.

Patented Oct. 6, 1914.

I To all whom it may concern:

Be it known that I, JAMES ARTHUR SING- .uAs'rnR, a citizen of the UnitedStates, residing at Palmerton, county of Carbon, State of Pennsylvania,have invented certain new and useful Improvements in the Manufacture ofZinc Oxid; and I do hereby declare the following to be a full, clear,and exact description of the invention, such as will enable othersskilled in the art to which it appertains to make and use the same.

The object of the invention is to provide a practical method ofproducing zinc-oxid by a continuous operation and in such a manner thatthe subliming reactions, socalled, will be effected with a higher degreeof chemical and mechanical efiiciency than is possible with thewell-known form of l/Vetherill furnace.

More particularly, the object of the invention is to save fuel andlabor, to increase the percentage of yield from the charge and improvethe uniformity and purity of the product, to simplify the operations andapparatus required for handling the raw material and the residuum, "and,further, to ameliorate the temperature conditions to which the workmenare subjected.

According to my invention, the charge 1s placed on a moving conveyance,specifically formed as a traveling grate-surface, and advanced throughthe combustion zone of the furnace apparatus, wherein the desiredreactions take place .with uniform and constant combustion and completeutilization of all the valuable elements of the charge. The workmenprepare the charge, consisting of fuel and ore, flue-dust, or othermetallic compound to be treated, and place it on its conveyance outsideof the furnace or at a point within it which is sufficiently removedfrom the active combustion zone to enable them to work carefully andwithout discomfort or dan er. According to the nature of the materia tobe treated, the charge may be spread on a layer of bed coal, which hasbeen ignited,or it may be deposited on the conveyance in any othersuitable way, while the conveyance is advancing into or through thefurnace, ignition of the fuel being produced either by special means tothis end or spontaneously by the heat of the zone; and, coincidentlywith the advancing movement, a suitable combustion-supporting gas, suchas air, is transmitted to or through the charge in controlled amounts tothe end of properly generating the fume from the zinc or from the othervolatile .metal in the charge. After the fume generation has ceased, theconveyance moves out of the combustion zone, bearing a residuum ofbarren clinker and ash, which is given 0 port-umty to cool before itemerges from t e structure, and is required to be handled by theworkmen. The efliuent is drawn ofi' durmg the passage of the charge andconducted to appropriate receivers. The preliminary efiiuent, being agas of the general character of producer-gas, and having little or nometallic content, is or may be conducted to a point separate fromthefume.- collecting means, where its fuel value may be utilized, or it maybe wasted if preferred; but in either case the receivers for thesublimed product are not burdened with the necessity of cooling andfiltering this high temperature and non-metallic part of the efiluentfrom the charge. The preliminary metalliofume efiiuent, being theefiiuent evolved in the initial stages of the reac-' tion, is usuallymore or less impure and oil'- color as a pigment, and for this reason ispreferably conducted and recovered separate from the subsequentlyevolved fume. The fume rising from the charge after it has reached thestage of full combustion, is transmitted to bag-houses or other suitablescreening system for collection in the usual way. It is important thatthe fume constituting the objective product of the process be taken awaypromptly from the subliming region and therefore the screening andcollecting system is connected with such region through a plurality ofsuitable off-takes distributed at intervals alon the path of travel ofthe fuming charge. hese off-takes may all lead to the same receiver, ifdesired, with or without a suction fan to move the fume through them;but it will be obvious that they can be connected singly or in grou s toseparate receivers so that not only the me containing sooty particles,if any such remain, can be kept separate from the white fume, but alsofumes of different compositions can be so arately collected from thesame charge. t is b virtue of this method of removingthe e uent from thetraveling charge, that bituminous coal can be used as the fuel, as abovestated.

' supplied to in bustion progresses and such movement contain thegreater part of the sooty combustion products, and what remainsthereafter will pass either into the first or second succeedingofi-takes which are in this case, of course, connected with separatereceivers.

The combustion or sublimin zone above referred to, is preferablyconstituted by the middle part of a long, stationary, thickwalledchamber or tunnel which is raised to the necessary high temperature bythe heat of the reactions taking place therein, and is maintained atthat temperature by the continuing passage of the charge, without beingallowed to cool down until the end of the run, thus establishingpractically constant temperature condition and a consequent high degreeof uniformity in the quality of the product pigment. The traveling ratesurface on which the charge is carried, is divided into sections, aslater described, each following the other and each provided with its ownair supply connections which are subject to control by the operator soas to maintain a proper temperature of charge and furnace, and asutlicient excess of ex gen above the charge to oxidize the volatilizedmetal or metals. As in the established Wetherill practice, the air thatis the charge is increased as comthe charge advances. Further control ofthe generation of the fume can be had in the present invention byvarying the suction in the od-takes and by varying the rate of movementof the charge,

being accelerated or retarded, as the case may be, in accordance withthe conditions developing in the charge as observed through suitableopenings in the tunnel side walls. may, of course, be continuous orintermittent according to circumstances, and it will be seen that by theexercise of proper judgment in the regulation of the controlling factorsthe conditions that are now known to be most productive of economy ofoperation and of high quality of product in Wetherill furnaces canobviously be reproduced by my present process in continuous form, andthat such conditions can also be maintained with a high degree ofreliability and precision.

In the mixture constituting the metal lie compound to be reduced andvolathe fuel ingredient (which may be either anthracite coal orbituminous coal) will necessarily be somewhat larger in my method thanjust suthcient for the generation of the necessary heat and thereduction of the metal, and my invention further contemplates thetreatment of the charge after the volatile metal has been extracted torecover and utilize the energy of this excess. By continuing the aircurrent through the charge and moving the latter tea point beyond thesnbliming zone,

that the continuous process The advancing movement niiaees the fuelremaining therein is converted into gas which I conduct back to thefurnace at an earlier point in the path of the charge, or utilize insome other manner, as will be later pointed out. This gas may, ifdesired, be mixed or used in conjunction with the preliminary,non-metallic eflluent given ofi' by the entering ignited charge as aboveexplaine before it reaches the point of generation of fume.

From the outline of the principal features of my invention, above given,it will be seen readily leads itself to performance in duplicate ormultiple apparatus, whereby the grate sections leaving one furnacetunnel can be immediately dumped or cleaned and again nel, and Whilethey are still fairly hot, so that the ignition of the new chargethereon will be assisted and time as well as fuel saved.

The dehils of the preferred form of the method will be more fairlyunderstood in connection with the description of the ap oaratusillustrated in the drawings and described below. It is the object ofthis apparatus to provide simple and efiective means for transporting.and advancing a charge and for maintaining its temperature and thecontrol of the reactions, whereby uniformity can be obtained .andwhereby such manuallabor as is required to be performed thereon can bedone at a safe distance from the region of the intense heat. It shouldbe noted, and will be apparent to those who are skilled in the art ofsubliming metals, that both the method and the apparatus constitutingthe invention herein disclosed, are also applicable to the manufacfltureof sublimed metallic products other than zinc-oxid. r I

Referring to the drawingsz-Figures 1 and 1* together represent avertical, central and longitudinal section of a tunnel structureembodying the present invention and adapted to the method I have abovedescribed: Fig. 2 is an enlarged detail in vertical section through thetunnel and one of the grate sections,.on line lI- ll of Fig. 3: Fig. 3 atransverse vertical section of Fig. 2, the structure being here shown asa single tunnel structure: Fig. 4 a horizontal section on line INF-IV ofFig. 3. Fig. 5 a vertical longitudinal section on the staggered line V-Vof Fig. 3. Fig. 6 a horizontal section on line Vl-VI of Fig. 3. Figs. 7and 8 are respectively transverse and longitudinal I have devised,

loaded and entered into another tun-.

sections of the tunnel and one of the grate sections provided with amodified and preferred form of traveling air connecting means. Fig. 9 isa transverse section through a double tunnel furnace, also showing themeans for utilizing the heat of the residual gases of one for ignitingthe charge the ternal dimensions about 7 by 6 feet, subject tovariation, however, as circumstances may require. The length isdetermined with relation to the time required for completevolatilization and oxidation of all the zinc or volatile metal of thecharge during the movement of the latter through the tunnel at adefinite rate, a slower rate of movement requiring a longer tunnel, andvice versa. The tunnel is preferably somewhat longer than required toaccommodate the traveling charge while in the actual process ofcombustion, so that its end portions may serve asvestibules, so tospeak, of the actual combustion region, the entrance portion beingadapted to protect the charge during its formation and ignition, andtheexit portion to allow the exhausted charge to cool off before emerging,while the extension of the tunnel at either end, beyond the limits ofthe actual combustion zone, operates to conserve the heat developed bythe reactions in the latter. In the drawings, the length of the tunnelis reduced for convenience, by breaking out intermediate parts, but theportion constituting the active combustion zone is indicated in ageneral way by the location of the off-takes which are for carrying awaythe gaseous product and fume. terior of the tunnel is provided with aseries of partitions 2, dependingfrom the roof, with their lower edgesextending as close as may be to the top of the charge moving thereunder.These partitions serve as baffies obstructing movement of gas betweenthe combustion zone and the ends of the tunnel, and divide the upperpart of the tunnel into a series of inverted pockets or collecting hoodsinto which the fume from the charge rises and from which it iscollected. In Figs. 1 to 10, the partitions are formed by archedcurtain-walls sprung from the sides of the tunnel, as shown more clearlyin Fig. 3, but in the modified tunnel structure of Fig. 11 the sameeffect is produced by forming the tunnel roof of a series of successivearches 3 with their axes transverse to the direction of the tunnel andtheir springers rested on cross beams 4 spanning the side walls of thetunnel. The cross beams and their enveloping masonry, being situatedjust above the course of the charge, serve the same purpose as thebaflie partitions 2 of the form first described. Water The inpipes,indicated in section at 4 in Fig. 11, are laid alongside the beam 4 toguard against their overheating.

The partitions, formed in either way, are located at intervalsthroughout the length of the tunnel excepting at the entrance end wherthey may be omitted to provide space for c argin Throughout the portionof the tunnel where the charge is in combustion, they are spaced apartat substantially regular intervals of say about 12 feet, and from eachof the intervening pockets leads an off-take for the efliuent gas orfume. The first off-take 5, is adapted to conduct the preliminarynon-metallic efliuent which is given off by the charge after ignitionbut before volatilization of metal has begun. There may be severaloff-takes for this kind ofeflluent but only one is illustrated in thedrawing. It or they may lead to any suitable collector or to a chimneystack, but as above mentioned the preferred method of operationcontemplates the utilization of these gases for heating or igniting thebedcoal, and for this purpose a down-comer 6 is provided for thestructure shown by Fig. 1 leading to the chamber or region of the tunnelwhere the charging operation takes place. The gas is directed toward thefreshly-laid fuel bed together with the air necessary for itscombustion,- and the heat thus genera-ted is made use of to ignite thefuel. In case this fuel supply should not be suflicient for thispurpose, as may be the case in starting the apparatus in action, I havearranged an auxiliary furnace, indicated diagrammatically at 6 in Fig. 1which is adapted to provide suflicient heat to insure ignition of thefuel. The combustion gases of the ignition stage may be wasted in any.suitable way. The second off-take 7 considering them with reference tothe advancing movement of the, charge, is intended to take away thepreliminary metallic effluent, being for this reason entirelyindependent of the remaining off-takes. It may lead to a bag-house orany other suitable receiver not shown in the drawings. The nextsucceeding off-takes 8 lead off from the part of the tunnel wherethe'subliming actions takeplace and are for the fume resulting from theperfect reactions of the charge. These off-takes may all be conncctedwith a common pipe or flue 9 running to the bag-house or, where thematerial under treatment is capable of fractional subliming, thesuccessive off-takes can be separately used for collecting the differentfumes evolved. Dampers are diagrammatically indicated at 40 in eachoff-take for conway 12 laid on the floor of the tunnel, and is of asuitable width to extend from sidewall to side-wall of the tunnel withonly a running clearance on either side. The successive grate-sectionsor their supporting frames are adapted to move in end-wise contact witheach other, so that they will form a moving and substantially continuoushorizontal deck or partition, dividing the upper from the lower part of.the tunnel with no appreciable gap or openingbetween them. The clearancespaces at the sides of the traveling sections are preferably sealed bylutes. These may consist of troughs 13 carried on brackets on thesidewalls of the tunnel and filled with sand or other heavy and mobilematerial. The grate-sections have aprons 14 depending fromtheir lateralmargins-and projecting into the sand so as to form a continuous closure,adapted to accommodate the movement of the sections without leakage. Theparticular mode of mounting and guiding the sections through the tunnelis not of special consequence and various other means than the wheeledtruck frame can manifestly beused with like effeet, but the wheeledtruck frame or buggy, such as shown, is preferred because of the lengthof the tunnel and the load which must be carried through it. The lowerpart of the tunnel is open to the. circulation of the outside atmosphereand is therefore not so heated as to injure the running gear of thesedevices. Each truck frame is a rectangular frame about 12 feet long witha free space in the middle for the accommodation of the air supplyapparatus and the water basin. The side sills, marked 15, are bornedirectly on the journal boxes 16 secured to them, and are joined attheir ends byithe cross-sills 17. On the top of each side sill, there isplanted a series of slotted brackets 18, and across the rectangularframe there is laid a series of eight or morebearer-bars 19 rested withtheir ends in the slotted brackets, so that their top edges occupysubstantially the same horizontal plane. A plurality of separate andremovable grate bars, each about 9 inches wide and perforated, such asare at present used in zinc-oxid furnaces, are laid side by side uponthe bearing bars with their ends supported in the angles of the Z-bars20, of which there is one at each end of the frame, to hold the gratebars from longitudinal movement on the frame. The two grate bars locatedat the sides of the section, and marked 10 are preferably secured to theframe, so that they will hold the intermedi-- ate removable bars fromseparating laterally. The several bearer bars 19 support the grate barsagainst sagging when highly heated under the weight of the charge, andthese bars are formed in simulation of knife edges, as shown, so thatthey will perform this function without unduly obstructing the grateperforations. These juxtaposed grate bars as thus supported constitutethe grate sectionabove referred to and the succession of these sectionsconstitutes the grate of the furnace. Upright walls are preferablyconstructed on the margins of each section to confine the charge thereonThe fixed grate bars 10 have placed-upon them the bars 21, each of whichis specially shaped to hold a row of refractory blocks .22 forming aside wall on each side of the grate; and end walls therefore aresimilarly provided by the bars 24 and the refractory blocks 23 heldthereby, the four walls being preferably removable from the gratesection so that they can be lifted ofi separately or all together, toallow the clinker to be removed and the grate bars to be cleaned. Thewalls assist in the production of uniform quality of product by thefacility they provide for leveling the charge of with a uniform depth,equal to their height, over the surface of the grate and they also serveto retain and confine the heat as well as to avoid theerosion of theinner surface or lining of the furnace, which would otherwise take placeif the stationary sides of the tunnel were relied on to keep the chargeon the grate.

The rate bars form the roof or covering of an air chest 25 formed ofsheets of iron in the present instance, with sloping side walls whichare secured by their lateral upper margins to the side sills and bytheir end margins to the depending flanges of the two end Z-bars 20. Thespace between the side sills and the fixed grate bar 10* on one side isclosed in by the curved wall 26 (Fig. 3) while the correspondingspace'on the other side is left open for the admission of the air, whichon enterin the chamber passes thence upwardly throug the perforations inthe bars and through the charge thereon. A. hand-hole, in the form of aflap-door 27, normally closed air-tight, is provided in the sloping wallat one end of the air chest, for cleaning it of ashes or portions of thecharge that may fall through the grate; and the portion of the air chestthat depends below the level of the cleaning door forms a basin whereinwater is or may be contained, during the operation of the section, thisbeing for the purpose of guarding against excessive temperature in thegrate.

Admission of the air to the air ohest'25 is accomplished by means of adevice herein termed a traveling air conneetor, since its function is toform a connection between. the charge conveyance with which it moves,and a stationary source of air supply, or a series of such sources,disposed along the path through the tunnel. This device is susceptibleof embodiment in a variety of forms and may be used with forms of furtheone under description.

dimension to the length of the frame, and

connected at' its top with the air admission space of the air chest. Forthis purpose its upper margins may be secured respectively 'to the fixedgrate-bar 10 and the top of the adjacent side-sill, as shown, and it mayalso be stayed to the journal boxes so that it will constitute a rigidstructural part of the vehicle. Its lower end opens inside of a troughor gutter 29, which is filled with liquid such as water and extends thefull length of the track-way through the tunnel and parallel therewith.This trough or gutter, though shown below the level ofthe track rails,could be equally as well placed above that level. At intervals less thanthe length of the grate sections, the trough 29 is provided with uprightair pipes 30 connected from beneath with the valved branchpipes 31 of amain air header 32 which is supplied with air under pressure from a fanor like device shown in Fig. 4. The upright pipes from a series ofstationary air supply points throughout the length of the tunnel, one ormore of which is adapted to project upwardly into the box-like pipe 28,of the grate sectiondelivering air thereto, while the surrounding liquidfurnishes a seal to the connection between the two. At its front andrear ends the box-like pipe is provided with hinged flap-doors or gates28, partly or wholly submerged in the sealing liquid and adapted to rideover the tops of the upright air supply pipes as the vehicle advances,thus establishing air communica= tion with the successive air pipes. Itis desirable that the space between the adjacent supply pipes be suchthat there will be at least one communicating with each air connector atevery point in the movement of the latter through the tunnel so that theair communication with the air-chest of each section will be continuousduring the subliming process and under control.

It will be understood that all of the sections of the grate aresimilarly equipped with individual air supply connections of the kinddescribed or the equivalent, so that as each is detailed to service itmay move on the track-way through the tunnel with its air connectortrailing through the water seal trough 29, each truck abutting closelyagainst its adjacent trucks in front and rear, so that the successivegrate sections of each truck form a continuous traveling chargecarryingdevice as above described. The air connector pipes of each truck alsoabut or nearly so, so that the escape of air through the intervalbetweenthem when riding over a supply pipe will not be excessive. Thetrucks may be propelled by any means suitable for the propulsion ofvehicles, as for instance by a cable, but I prefer a pushing device suchas the ram 33 indicated in Fig. 1, because the successive sections canbe thus more readily kept in close contact with each other with noappreciable gap between them, but with other modes of propulsion, meansfor positively closing the intervening spaces can be readily added whendesired. Switching devices and suitable trackaga not shown herein, areintended to be rovided for introducing'the trucks in position in frontof the pusher. The track through the tunnel is preferably on a lowerlevel than that in the yard and approaches, so that the trucks will movedown an incline, indicated at 52 (Fig. l), as theyenter the tunnel andthus bring their connectors and lute aprons 14 into the proper relationwith the water and sand troughs, moving up a similar incline, at theexit, as shown at 53, to disengage these parts.

The grate, sections are preferably loaded with their charge as theyenter or while they are within the tunnel, and for this purpose I haveshown two hoppers above the tunnel roof; the one nearest the entrance,marked 34, is supplied with the fuel to form the bed, which fuel passes,under control,

pressible spreader 35, manipulated by the" lever diagrammatically shownat 36 or by any equivalent or suitable gearing, to cause the fuel to bespread in an even layer over the grate as the latter advances. As thegrate surface thus covered with fuel comes under the second hopper 37,it receives therefrom a layer of mixed fuel and one or such compound ofzinc or of such other metal as may be the subject of the treatment. Thishop per also is associated with a spreader 38, under the control of theoperator, by which the charge is leveled off even with the tops of theside walls in the obvious manner.

In the drawings, the construction of the hoppers, their controllingdevices and the Spreaders, is indicated merely in a conven tional way;it will be understood that any suitable mechanical appliances can beused for these urposes.

Being tlius continuously loaded with a uniform layer of charge, thesections are continued in motion and pass toward and through theintermediate and highly heated part of the tunnel, heretofore designatedas the active combustion zone. In starting the apparatus after a periodof idleness it will be necessary to ignite the entering charge by meansof the special heating means above described and shown at 6 in Fi 1,until the furnace is in full operation, a ter which the preliminaryeffluent from the downcomer 6 can be used for this purpose, or the gasfrom the residuary fuel, after completion of the fume generation asabove stated.

By proper regulation of the valves in air pipes 31, the air supply toeach moving grate section is controlled in accordance with the observedhysical and thermal conditions of the c harge, the supply beingincreased as the combustion progresses. It will be understood that thean for each section passes thereto through the successive supply pipes30 inthe water seal, one or more of these pipes being constantly incommunication with the connector arm of ear-h grate section. Thecontrolling valves in the branch pipes 31 are located along the tunnelso as to be conveniently operable fr m a position adjacent the door-ways39,

ihlough which the action of the charge is observabie so that theadjustment of the aar supply can be promptly efiected. When the metalhas become completely volatilized from the charge on a given gratesection that section will have reached a point in the tunnel beyond thelast ofi-take 8, and the of fluent rising therefrom, 'resultmg from thecontinuing combustion of the fuel stillremaining in the. charge, isallowed to pass through a lateral flue 4:2 in the side-wall of thetunnel, and thence either to a chimney stack or to some point where theheat there-, in can be utilized. At the point where the combustion ofthe remaining fuel has ceased or diminished and the air supply isdiscontinued, the grate sections pass under a pendent screen 43 hangingfrom the roof of the tunnel near the exit, which screen they push aside,as shown in the drawings. .This screen and the two spreaders 35 and 38all coiiperate in closing in the ends of the tunnel structure above thelevel of the grate sections and they are each constructed with this endin view. The length of the tunnel beyond the pendent screen can ofcourse be continued as far as desired, and at the terminal thereofsuitable mechanism will be arranged for removing the now exhaustedcharge.

The duplication of the tunnel apparatus referred to above is illustratedby Figs. 9

' and 10 and its construction will be obvious from a consideration ofthese figures, both tunnels being exactly alike except as to thereversal of their direction.- Having a common dividing wall 45, the twoadjacent tunnels are, of course, more economical of heat than eitherwould be if built separate. The formation and arrangement of the gratesections and their truck frames and the air connectors of each frame maybe the same as already described, but the propelling means of whateverkindjemployed, .is arranged to move them in opposite directions throughtheir respective tunnels so that the unloaded trucks of one tunnel canbe immediately recharged and turned into the adjacent entrance of theother with the least loss of time'and heat and the miniconnection.

angers mum of trackage and appliances. A loop of track or a turntable,not shown, may be used for shifting thetru'cks from one tunnel to theother.

The portion of eachof the adjacent tunnels, between the last fumeoif-take and the pendent screen, is connected, by a lateral flue heremarked 46, leading through the dividing wall 45 into the enteringportion ofthe adjacent tunnel, where the grate sections are receivingtheir bed-coal, or where they pass after having received it, and thislatter portion of tunnel is connected with a stacker chimney 47. Thefuel remaining in the charge after volatilization of the metal, iscaused to burn while moving in the portion of the tunnel above referredto by continuing the supply of air through the travelin air-connector,and the products of combustion escape through the lateral opening 46into contact with the freshly laid fuel in entrance portion of theadjacent tunnel, where they may mingle with the preliminary non-mteallicefliuent if the same is used for igniting the fuel. The escape from thispart of the tunnel is through a chimney 47.

The modification of Figs. 7 and 8 concerns only the form ofair-connecting means, the construction of the tunnel and the truckframes and their grate surfaces and air chest being otherwise the sameas above described. The air supply disposed along the track through thetunnel, comprises an inverted trough-like box or hood 48, co-extensivein length with the trough .29 which, as above described, runs the lengthof the tunnel. The open side of the hood is immersed in the water intrough and its interior is divided into compartments by 'a series offlap-doors 49 hingedtherein so that the effect of gravity will maintainthem in closed position. Each compartment is connected through its sidewall, with one of the valved branch pipes 31 of the main air header 32,so that the pressure in each of the compartments or the volume of airpassing thereto can be varied at will and eachindependently of theothers. The air connector for this form of air supply consists of agoose-neck pipe 50 connected by its upper end with the air chest 25 andterminating at its lower end in an upward extension 51 projecting withinthe hood t8 and reaching the space therein above the water level, sothat it can receive the air from the respective branch pipes 31 whilethe surrounding water forms the seal to the As the grate section travelsalong the track, the lower end of the gooseneck pipe will push upon andopen the successive compartment doors 49, which will close behind it,and preserve the isolation of each compartment, except for the momentaryinterruption when the pipe passes from stant communication with the airsource,

and in each of them the air will be under control by the" manipulationof the, air

valyes, so that it can be made to increase asthe charge advances or asdesired. Ordinarily the supply to several compartments will bepermanently set or adjusted to provide the appropriate increase in thesupply to the trucks as they advance and without attention by theoperator. The compartments of the inverted hood would then contain airat differential pressures properly coordinated to the advance of thecharge. The goose-neck form of traveling air-connector is preferablyhinged and telescopic, so as to be capable of being removed or turnedback out of the waywhen the truck is being shifted about the yard, andit is hence more convenient than the form first described. One of thesaid pipes is sufiicient to maintain constant communicationwith thefixed air source, but two or more of such pipes can be used with eachtruck frame, as indicated in the figures referred to. It is desirable,however, that the air boxes of the successive frames, when supplied withmore than one air connector pipe, be arranged so that they will not putmore than two of the compartments in the hood 48 in communication at thesame time. This is accomplishedby the proportioning of the spacesbetween the fiap-doors 49 with reference to the spaces between the airconnectors.

It will be understood by those skilled in this art that the apparatusabove described is not limited with respect to the size or proportion ofthe tunnel structure, or its grate-sections, nor to the details of theirmechanical assemblage or construction, nor to the number of air boxessupplied to the section of the grate surface that is borne by eachtruclcframe, and that various omissions, substitutions, and alterationsin the form and in the operation of the apparatus may be made withoutdeparting from the invention.

I do not claim herein. the apparatus shown, for the reason that I havefiled a separate application for Letters Patent of reducible compound ofthe zinc or ot er relatively volatile metal and combustible material,igniting such bed, advancing the same during its combustion through asuitable chamber, simultaneously transmitting a combustion-supportingdraft-current through the bed, and collecting the effluent from such bedat successive points along its path of movement.

2. The process of producing sublimed zinc oxid and analogous products,which consists in forming a bed or layer comprising a reducible compoundof a relatively volatile metal and combustible material, advancing thesame through an inclosing tunnel, previously heated to cause ignitlonand com bustion of said bed or layer, simultaneously transmittingthrough said layera combustionsupporting draft-current during its travelthrough said tunnel and collecting the efiiuent from said bed or layer.

3. The process of producing sublimed zinc oxid and analogous products,which consists in forming a bed or layer comprising a reducible compoundof a relatively volatile metal and combustible material, igniting andadvancing the same through a suitable combustion region; simultaneouslywith such movement transmitting an air current through said bed orlayer, increasin such air supply coincidently with the a Vance of saidbed or layer and collecting the eflluent from the latter.

4. The process of producing sublimed zinc oxid-and analogous products,which consists in forming a bed or layer comprising a com pound of arelatively volatile metal, advancing the same through a heated zone,

simultaneously with such advancing motion ent arising in the earlystages of the ensu ing combustion, advancing such bed or layer duringits combustion and separately collecting the metallic efiluent.

6. The process of manufacturing zinc oxid, comprising iproducing anignited bed of a compound 0 zinc and a fuel, advancing such bed througha suitable inclosing fume-collecting chamber, supplying a combustionsupporting draft-current through said bed during its movementtherethrough, increasing the pressure of such current as the movementprogresses, conducting away the preliminary effluent fromsuch bed, andseparately conductin and collecting the subsequent metallic e uents.

7. The process of manufa cturingvzinc oxid, which consists in producingan ignited bed or layer of fuel and a reducible compound of zinc,advancing and simultaneously driving off metallic fume from said 7' ingthe residuary efliuent.

. 8. The process of manufacturing zinc oxid or like product whichconsists in producing a continuous bed or layer of a com-' pound ofz'ihc, advancing and simultaneously driving off zinc fume therefrom, andcollecting such fume, collecting the residuary eflluent from said bedand conducting the latter into contact with a similar freshly preparedcontinuous bed or layer of zinc compound to assist in igniting the same.

9. The process of manufacturing sublimed zinc pigment, consisting informing a charge comprised of a bed or layer of fuel and a superposedlayer containing acompound of a relatively volatile metal, igniting andadvancing such charge through a suitable combustion zone, simultaneouslysupplying the same with a combustion-supporting draftcurrent andcollecting the metallic fume from the advancing charge.-

10. The process of manufacturing sublimed zinc pigment, which consistsin main- ,taining a tunnel of refractory material in a driven off fromsaid charge during its said advancing movement.

In testimony whereof I ailix my sigirlatur:- in presence of two.witnesses.

JAMES ARTHUR SINGMASTER.

Witnesses:

JOHN C. PENNIE', M. A. -BILL.

